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Feb. 10, 2011 -- Warming local anesthetics may reduce the pain experienced during injections, a new study finds.

“Warming an injection is a cost-free step that emergency physicians can take to reduce pain from a shot,” study author Anna Taddio, MD, of the University of Toronto, says in a news release.

“Patients often dread the sight of a needle, but doing something as simple as warming the injection to body temperature can make a painful part of an emergency department visit more tolerable,” she says.

The study authors write that local anesthetics are the main type of analgesics used for pain management during laceration repair and other minor surgeries.

When the anesthetic is injected, a burning or stinging sensation may occur.

Analysis Finds Less Pain With Warmer Anesthetics

The research team reviewed data on 831 patients in 18 studies, finding that warming injections produced a “clinically meaningful reduction in pain,” whether the amount of anesthetic being injected was large or small. The injections were warmed using controlled water baths, incubators, fluid warmers, baby food warmers, a warming tray, or a syringe warmer, the researchers say.

The analysis concluded that warming local anesthetics on average reduced pain by 11 mm on a 100 mm scale. They note that anecdotal evidence suggests that some emergency doctors warm injections in their hands before administering shots.

The study is published in Annals of Emergency Medicine.

“Future research should examine the effects of warming local anesthetics for dental procedures and for procedures involving children,” Taddio says. “This is an area where a small change may make a big difference for a patient.”